The formation of colored coatings on various supports by application of a colored composition to these supports followed by drying and thermo-cross-linking has been known for a long time. This prior art technique has a number of disadvantages including bulky installations, a large energy consumption owing to the fact that it is necessary to remove the solvent and heat the support and the coating, possible deterioration of the support during the treatment or at least alteration of some of its properties, and problems of safety and toxicity connected with the use of certain solvents.
It has also been proposed in the prior art to replace the thermo-cross-linking by photo-cross-linking; i.e. cross-linking under the influence of ultra-violet rays which considerably restricts the above disadvantages.
However, whether photo-cross-linking or thermo-cross-linking is used, the colored compositions used so far in the prior art for coatings contain, in the form of different entities, a cross-linkable colorless polymer on the one hand and a pigmentary dye on the other hand, which exhibit the following disadvantages:
the necessity to put the dye in pigment form, which is often difficult, lengthy and costly. PA1 during the storage of the compositions, the dispersed pigment can separate or undergo undesirable changes such as crystallization or alteration of physical form. PA1 the pigment remains chemically independent of the coating after the cross-linking and may then migrate, with resulting loss of quality of the coating and possibly problems of toxicity. PA1 during the photo-cross-linking, the solid particles of pigment absorb a considerable amount of light energy, which necessitates increase in the time of irradiation and/or the amount of photo-initiator in the compositions. The increase in the quantity of photo-initiator has a very unfavorable influence on the stability on storage of the compositions and somewhat reduces the quality of the coating as a result of heterogenity due to the photo-initiator residues. PA1 and R.sub.1 and R.sub.2 are the same or different and represent hydrogen, chlorine, methyl, phenyl, substituted phenyl or carboxyl; PA1 m is a number from 0 to 49 and PA1 n a number from 2 to 70 PA1 such that the sum m+n is from 7 to 70 PA1 and the ratio m/n is from 0 to 2.4. PA1 a colorless polymeric base containing polymerizable ethylenic double bonds PA1 mono or polyfunctional (i.e. having one or more polymerizable ethylenic double bonds) acrylic monomers PA1 one or more photo initiators PA1 one or more adjuvants PA1 a pigment.